Embodiments of the invention relate to a propeller of a rotary wing aircraft, and more particularly, to reducing the noise generated by the propeller during operation of the aircraft.
Propeller driven aircrafts have near field and interior noise that include noise signature content related to operation of the propeller. Near field noise outside of the aircraft can create pressure fluctuations that may fatigue the structure of the aircraft. This near field noise can also result in interior noise, audible within a cabin of the aircraft, making the aircraft less comfortable for passengers situated therein. Propeller noise will also propagate to the far field becoming an annoyance factor for those living near an airport.
Various methods have been employed to reduce propeller noise, including the use of swept blade propellers, increased blade count, active noise control, and tuned mechanical dampers within or on the fuselage. On multi-engine aircrafts, angular phasing of the propellers has long been used to alter the characteristics of the propeller noise perceptible within the fuselage. In spite of the various methods used to reduce noise generated by the propellers of a propeller driven aircraft, there remains a need for further improvement.